PTH and chronic kidney disease: Comparison between patients with ESRD and patients with CKD showed non-significant differences except for levels of urea (p = 0.002), creatinine (p < 0.001), PO4 (p = 0.016) and PTH (p = 0.002) which were higher in the ESRD group, while serum calcium level (p = 0.023) was significantly lower in the ESRD group.